1. Field
The disclosed method and system relates to a facsimile apparatus. More particularly, the disclosed method and system relates to a facsimile apparatus which is capable of properly performing a facsimile communications operation using optional frames without causing a communications error.
2. Description of the Related Arts
There have been developed facsimile machines capable of performing a facsimile communications operation in accordance with the international Group-3 facsimile communications standard, the recommendation T.30 (hereinafter referred to as the T-30) issued by ITU-T (International Telecommunication Union; T sector). The T-30 has been updated from time to time with additional specifications and thus includes several optional frames such as SEP (selective polling), SUB (sub-address), PWD (password), and so on.
The frame PWD is defined in a selective polling mode as a signal for indicating that the following facsimile information field (FIF) represents a password for allowing entrance to a selective polling mode, which can be used for additional security to the facsimile communications procedure. The frame PWD is also defined as a signal for indicating that the following FIF represents a password for allowing transmission of facsimile information during the regular communications mode.
The frame SEP is defined in the selective polling mode as a signal for indicating that the following FIF represents a sub-address to be used in the selective polling mode, which can be used as an indication of an event that a specific document will be polled at the called facsimile machine.
The frame SUB is defined in the normal communications mode as a signal for indicating that the following FIF represents a sub-address assigned to a terminal machine within a domain where the called facsimile machine is located, which can be used as additional routing information in the facsimile communications procedure.
Such an addition of the optional frames to the Group-3 facsimile communications protocol particularly improves the polling mode operation in the facsimile communications procedure. For example, it becomes possible for a calling facsimile machine in the polling mode to easily select receivable image information files as well as to enhance the level of information security. Also, it becomes possible for a calling facsimile machine in the polling mode to designate a destination terminal to which the files are to be transferred. For example, when a calling facsimile machine is coupled to a local area network, it can use the optional frames to designate a destination terminal at which the files can be received.
However, the facsimile machines which use the above-mentioned optional frames have a problem. As described above, the recommendation T-30 defines the optional frames from the functional point of view. However, the T-30 does not define the way the optional frames are to be used. Accordingly, the manufacturers of such facsimile machines need to establish an agreement on the usage of the optional frames. This is a way to ensure the performance of the facsimile communications operation between the facsimile machines manufactured by different manufacturers without causing problems. However, some manufacturers do not necessarily participate in the agreement and, therefore, freely produce facsimile machines which may not conform to the common specification of optional frames. Accordingly, these non-conformable facsimile machines may cause a facsimile apparatus a problem in a communications operation.